Besides the answer above, if it does not work:
Has the installation process already installed the two shelf icons on the Maya shelf? If so, restart Maya, click on the shelf button, it will again pop up a dialog that prevents you from loading the tool. Go to the Security panel, choose "allow anyway" as show below.
Then go back to Maya, click on the shelf again, see it will probably pop up with a dialog with the Open button.
The problem was, If you keep installing it, the .bundle file gets updated again as part of the installation process and the security panel needs to allow the new version of the bundle file again.